Help with High Velocity Weizen

This was my first time doing a beer that uses yeast that requires lower temp. I have had it in the fridge for almost four weeks and the time between air lock burps is still around 10 seconds apart. I know that lagers take longer to ferment just wandering if anyone has some suggestions. This is a wheat recipe that called for ale yeast and I used a lager style and the average temp in the fridge has been 40-50 degrees.

I used an unmodified frig. to ferment one of my first lagers. The temp. was too cold for a strong primary fermentation and just lingered forever and never seemed to finish. Recently I tried to recalibrate a t-stat out of a frig and could not get it to go above 40 degrees. If you are using an unmodified frig. you would be doing good to hit 40 degrees. If you are measuring the ambient temps you will get large variations in the readings. Something like a 5 gal batch of beer will have a more consistant temp. With my modified chest freezers I keep a thermometer in a 2 liter bottle of water to minimize the wild readings. I also pack any extra space with bottles of water and beer to keep a more consistant temp.

Thank you for your suggestions. I did a little reading on lager yeast temps and it can take a couple of months for some to finish fermentation. I will be patient and slowly turn the temp to a warmer setting. It is a old full size fridge I turned into a beer fridge with a corny keg system kept on the porch. I cant wait!!!!!
Those ale beers are less tricky and quicker than the lagers. I am doing another batch tomorrow and dont know which way to go...Stout/Porter or lager beer. Thanks again.

After almost seven weeks in the fridge I transferred the lager into a keg and sampled some of it. Holy crap was it yummy. Compared to the stouts I usually make this tasted like water. The key was time and patience. But way worth the wait.